Micro or nanoparticles with different compositions and chemico-physical properties can be used for delivery of active agents, such as therapeutic or imaging agents, see e.g. LaVan D. A., et al. Small-scale systems for in vivo drug delivery. Nat. Biotechnol. 2003; 21:1184-91; and Ferrari M. Curr. Opin. Chem. Biol. 2005; 9:343-6. Examples of such micro or nanoparticles include nanospheres, where a pay-load, such as drug molecules or imaging agents, is dispersed within a polymer matrix, see e.g. Duncan R. Nat. Rev. Drug Discov. 2003; 2:347-60; multilayered nano/microcapsules and liposomes, where the pay-load is contained in the internal capsule, see e.g. Crommelin D. J. A., Schreier H., Liposomes, pp. 73-190, in: Colloidal drug delivery systems, Kreuter J., editor, New York: Marcel Dekker, 1994; and nanoporous Si particles, where the pay-load binds to the pores surface, see e.g. Cohen M. H., et al. Biomed. Microdev. 2003; 5:253-9.
One of the advantages of micro or nanoparticles over free molecules administration may be their multifunctionality and engineerability. For example, micro or nanoparticles can carry a high load of therapeutic agent, which can be released with a precise dosage and scheduling, thus improving the efficacy and specificity of the therapy. The micro or nanoparticles can carry both therapeutic and imaging agents, so that the latter can allow monitoring the evolution of a disease or a physiological condition, such as a cancerous tumor, in vivo upon a therapeutic treatment. Surfaces of the micro or nanoparticles can have targeting moieties, such as ligands of different types that can increase the likelihood of specific recognition of the particles by a target site.
To execute its diagnostic and/or therapeutic mission, a micro or nanoparticle has to adhere firmly to one or more cells of a target site, such as a damaged cell. The firm adherence may be particularly important for targeting a vasculature site, as in such a case the adhesive interaction has to counteract the hemodynamic forces exerted over the particle by the flowing blood tending to dislodge the particle away from the surface of the target site, see e.g. Neri, D. and Bicknell, R. (2005) Nat. Rev. Cancer, 5, 436-446. Thus, a need exists to develop micro or nanoparticles with an enhanced adherence to a target site.